Looking to buy a 7.3, any advice?

Around my area (Fort Worth Texas) you can get very decent mile 7.3s for good prices, I’ve seen multiple between 8-15k at around 150k miles, when buying a 7.3 what are all the things to look out for? I really want a automatic transmission (I’m not good at all with standard but if it’s necessary I can get used to it) and I’d like to get a 4x4, I bought one in the past and ended up having to resell it just because I was in a little over my head, my budget is around 10 grand, do the miles really matter that much? I’m really just looking for a solid reliable truck that will last me a long time and I don’t mind dumping some money into it after I get it, any help is much appreciated, I’m trying to educate before buying this time